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Termini of calving glaciers as self-organized critical systems

 

J. A. Åström¹, D. Vallot^2*, M. Schäfer^3,4, E. Z.Welty5, S. O’Neel^5,6, T. C. Bartholomaus⁷, Yan Liu⁸, T. I. Riikilä⁹, T. Zwinger¹, J. Timonen^9,10 and J. C. Moore^2,3,8*

 

1CSC–IT Centre for Science, PO Box 405, 02101 Espoo, Finland.
2Department of Earth Science, Uppsala University, Villavägen 16, 75236 Uppsala, Sweden.
3Arctic Centre, University of Lapland, PL122, 96100 Rovaniemi, Finland.
4Finnish Meteorological Institute, PO Box 503, 00101 Helsinki, Finland.
5Institute of Arctic and Alpine Research, University of Colorado, Campus Box 450, Boulder, Colorado 80309, USA.
6Alaska Science Center, US Geological Survey, 4210 University Drive, Anchorage, Alaska 99508, USA.
7University of Texas Institute for Geophysics, 10100 Burnet Road (R2200), Austin, Texas 78758, USA.
8State Key Laboratory of Earth Surface Processes and Resource Ecology, College of Global Change and Earth System Science, Beijing Normal  University, Beijing 100875, China.
9Department of Physics and Nanoscience Center, University of Jyväskylä, PO Box 35, 40014 Jyväskylä, Finland.
10ITMO University, Kronverkskii ave. 49, 197101, Saint Petersburg, Russia

ABSTRACT

Over the next century, one of the largest contributions to sea level rise will come from ice sheets and glaciers calving ice into the ocean1. Factors controlling the rapid and nonlinear variations in calving fluxes are poorly understood, and therefore difficult to include in prognostic climate-forced land-ice models. Here we analyse globally distributed calving data sets from Svalbard, Alaska (USA), Greenland and Antarctica in combination with simulations from a first-principles, particle-based numerical calving model to investigate the size and inter-event time of calving events. We find that calving events triggered by the brittle fracture of glacier ice are governed by the same power-law distributions as avalanches in the canonical Abelian sandpile model2. This similarity suggests that calving termini behave as self-organized critical systems that readily flip between states of sub-critical advance and super-critical retreat in response to changes in climate and geometric conditions. Observations of sudden ice-shelf collapse and tidewater glacier retreat in response to gradual warming of their environment3 are consistent with a system fluctuating around its critical point in response to changing external forcing. We propose that self-organized criticality provides a yet unexplored framework for investigations into calving and projections of sea level rise.

 

PUBLISHED BY: NATURE GEOSCIENCE, 2014, 7 (12): 874-878

 

SOURCE: http://www.nature.com/ngeo/journal/v7/n12/full/ngeo2290.html